1. Field of the Invention
This invention relates to various types of drawing machines, such as tenters for processing a strip material, e.g. cloth or film, horizontal drawing machines used, for example, in a serial biaxial drawing line, and simultaneous biaxial drawing machines.
2. Description of the Prior Art
Drawing machines of the above type used widely hitherto will first be described briefly with reference to FIG. 5 which is a plan view of a somewhat schematic outline of drawing machines in general.
In this drawing, reference numeral 1 indicates a strip material (hereinafter referred to as a film) such as a film, which is stretched in the cross direction by the drawing machine. Reference numeral 2 indicates a pair of endless rails which are disposed fixedly on either side of the film to be stretched. Referencenumeral 3 indicates a number of paired clips mounted slidably on the pair of clips 3 arranged on either rail 2 are interlinked mutually by, for example, a roller chain in an endless fashion.
At the time of stretching, both selvage edges of the film 1 are pinched by the clips 3 in the inlet section A of the drawing machine, the film 1 is stretched in response to separation of the paired confronting clips 3 from each other while the clips are moving in the direction of the arrow C along the rails 2. The clips 3 release their pinching action in the outlet section B of the drawing machine, and the film 1 alone is sent outward from the drawing machine, while the clips 3 move successively along the outer path of each rail in the direction of the arrow E, and return to the inlet section A after circulating on the rails 2. The foregoing stretching action is then repeated.
The slide type drawing machine and the roller type drawing machine which are typical will now be described in detail.
Describing first the slide type drawing machine shown in FIG. 6, 1 is the film, and 5 is a clip body mounted on a clip base 8. 6 is a clip lever attached to the clip body 5 rotatably via a pin 7. The clip base 8 is substantially the rotated form of a letter U in cross section, whose concave portion accommodates a roller chain 9, so that each clip base is interlinked with adjoining clip bases 8. 10 is a rail body having an H-shaped cross section, the three faces of whose upper concave portion have respective slide sustaining plates 11, 12, and 13 secured thereto, so that the three faces of the clip base 8 are guided slidably.
Describing the action, the clip bases 8 are interlinked with one another in an endless fashion by the roller chain 9 and while keeping the synchronized relation between the left and the right sides, circulated continuously in the direction from the arrow C to the arrow E of FIG. 5 by means of a driving unit (not shown).
During the above operation, each clip lever 6 is pushed down in the inlet section A (FIG. 5) of the drawing machine by a clip lever lowering unit (not shown) to pinch the film 1 in conjunction with the surface K of the corresponding clip body 5, driven along the rail 2 in the direction of the arrow C of FIG. 5 to stretch the film 1, and in the outlet section B (FIG. 5) of the drawing machine, pushed up by a clip lever raising unit (not shown) to release the pinched state of the film 1.
The slide sustaining plates 11, 12, and 13 provided over the whole length of the rail body 10 allow sliding of the clip bases 8 while, supporting the stretching force of the film 1, the weight of the clips, and the like. Meanwhile, sliding surfaces L, M, and N are oiled by an oiling unit (not shown) to bring about lubrication.
Describing now the roller type, FIG. 7 shows the conventional roller type drawing machine, in which 1 is the film, 20 is a clip body, and adjoining clip bodies 20 are interlinked mutually by means of a roller chain 26. The clip body 20 of the roller type drawing machine has three rollers 23, 24 attached rotatably to respective vertical shafts 23a,24a in such a way that these three rollers hold a vertically-erected main roller support 28 therebetween. There is one roller 25 supported by a horizontal shaft 25a in such a way that it rolls on the horizontal surface of a rail body 27 on the side of the film 1. 21 is a clip lever which is attached rotatably to the clip body 20 via a pin 22.
29 is a rail receiver for supporting fixedly the rail bodies 27, 27a and the main roller support 28 erected between the former two.
In the roller type drawing machine of the foregoing configuration, its pinching and stretching action against the film 1 is identical to that of the foregoing slide type drawing machine; but, in this type of drawing machine the main roller support 28 provided over the whole length of the rail bodies 27, 27a supports the stretching force of the film 1 or the like, while the weight of the clips is received by the surface P of the rail body 27.
Meanwhile, the respective rolling surfaces P and R are oiled by an oiling unit (not shown) for lubrication.
Because the manufacturing process of the film being stretched and manufactured by the use of such a drawing machine is also adapted to manufacturing, for example, base films of material for condensors, and base films for photographs, a very high degree of cleanliness is demanded. In this connection, the conventional drawing machine, especially the slide type drawing machine, has the severe problem that the film is contaminated by dispersion of the lubricant.
Further, in the conventional drawing machine, noise is generated from the rolling surfaces and the sliding surfaces, thereby remarkably worsening the work environment. Especially, in the case of the slide type drawing machine, the problem that the consumption of power is extremely large owing to friction on the sliding surfaces arises.
Therefore, even if it is planned to operate the conventional drawing machine at a low energy consumption while keeping high the degree of cleanliness and of quietness, it is impossible to realize higher operating speeds.
As described hereinabove, according to the conventional drawing machines of these types, the scattering of lubricant and dust is severe while the machine is operating; as a result of such scattering, the quality of products is lowered and the work environment becomes worse. In addition, because the machine has a number of sliding portions owing to its peculiar configuration, noise is generated through sliding and contacting action, and power and energy losses become remarkably large in view of the sliding resistance.
Moreover, the foregoing problems become more severe at higher operating rates.